One image forming device known in the art has an electro-photographic image forming unit housed in an enclosure. The image forming unit has a photosensitive member that rotates about its shaft. Toner is supplied to the photosensitive member to form a toner image thereon. The enclosure includes a first wall provided on one side of the image forming unit with respect to a first direction parallel to the shaft of the photosensitive member. An air intake is formed in the first wall to allow air communication between the interior and exterior of the enclosure.
With this conventional image forming device, external air enters the enclosure through the air intake and flows toward the opposite side of the enclosure in the first direction. The air flows over the image forming unit at this time so as to cool the unit (Japanese Patent Application Publication No. 2005-17881, for example).